Apparatus for use in repairing commutators



Aug. 22, 1939. c. A. PAYNE APPARATUS FOR USE IN REPAIRING COMMUTATORSFiled Feb. 19, 1938 I M WN m N E INVENTO BY Patented Aug. 22, 1939 UNlTED- STATES PATENT OFFICE APPARATUS FOR USE IN REPAIRING COMMUTATORSApplication February 19, 1938, Serial No. 191,446

6 Claims.

In connection with the overhauling and repairing of direct current anduniversal motors and generators, it is usually necessary to re-surfacethe commutator. In the .case of small motors and generators,such asthose used in automobiles and in a greatvariety ofsmall tools, thisre-surfacing operation is readily accomplished either in alathe or withthe aid of special equipment commonly used by garage men. After theturning down of the commutator has been accomplished, however, it isnecessary, in order to produce a goodjob, to undercut the separators ormica plates interposed between the commutator segments. That is, theedges of these plates should a be cut down somewhat below the peripheralsurface of the commutator. The equipment now available for this purposeis expensive, and the present invention aims to devise'an inexpensiveapparatus with which this operation can be performed quickly andaccurately.

The nature of the invention will be readily understood from thefollowing description when read in connection with the accompanyingdrawing, and the novel features will be particularly pointed out in theappended claims.

Inthe drawing,

Figure l is a side elevation of an apparatus constructed in. accordancewith the invention, and

showing it in its operative position on an armature;

Fig. 2 is an end elevation of the apparatus shown in Fig. 1, itsrelationship to the latter figure being evident from the line 2--2, Fig.1;

Fig, 3 is a fragmentary, sectional view of the parts adjacent to thecutter, and showing the' cutter on a larger scale; and

Fig. 4 is a view similar to Fig. 2 showing a modification.

The construction shown in the drawing comprises a base 2 provided withan hexagonal portionto facilitate the mounting of it in a vise. Formedthrough this base is an aperture 3 and working in this aperture is aplunger 4 adapted to be moved up and down by means of a screw- 5, theupper end of the screw being secured rotatably in, but against axialmovement relatively to, the plunger 4; The uppersurface-of this plungercooperates with a V-shaped upper surface in the part 6 integral with thebase to form a clamp designed to receive the shaft 1 of the motorarmature 8, and to secure this armature in position for the undercuttingoperation.

Pivotally mounted on the base 2 is a reticulated arm or frame iii. Itstraddles the base and is secured to it by pivot screws l2|2 so that itcan swing in a plane passing through the axis of the shaft '1. A secondarm. I 3 is pivoted on the arm or frame I ll, the former arm preferablyhaving a hub portion l4 formed integral with it and located between theside pieces of the member I 0,

these two parts being secured together by pivot screws !5|5. This secondarm l3 also has a relatively long extension l6 formed integral with itwhich serves as a bearing for a shaft I! on one end of which the rotarycutter I8 is secured. A hand crank 29- is secured to the opposite end ofthe shaft and serves as the means for driving the cutter 8 in the formof the device designed to be operated by hand. Preferably the shaft [1is provided with a thrust collar 2| fast on the shaft and the cutter I 8is secured to the shaft by means of a screw 22 and washer 23. Betweenthe collar 2| and the cutter l8, and loosely mounted on the shaft, is asecond collar 24 designed to bear on the surface of the commutatorimmediately beside the cutter. This collar is somewhat smaller indiameter than the cutter and therefore limits the depth of the out whichcan be made by the cutter I 8.

It will be observed that the arms IE! and I3 are mounted to swing in thesame plane in which the cutter i8 is supported, and that this planepasses through the axis of the armature shaft 1. Also, that the natureof the construction is such that the cutter is held definitely in thisplane. This arrangement, therefore, supports the cutter for movementalong the surface of the commutator C, Fig. 1, where it can follow anelement of this cylindrical surface and thus can be traversed backwardand forward along the edge of a mica separator. The cutter used inworking on any individual motor will be of a width approximately equalto that of the separator. By revolving the cutter in the properdirection while it is so traversed, it can be made to cut the edge ofthe separator down to a depth below the adjacent surface of thecommutator controlled by the gage roll 24. Usually this depth in a smallmotor is approximately equal to the thickness of the separator.

For the purpose of holding the cutter pressed against the edge of theseparator on which it is working, a coiled spring 25 is interposedbetween the two swinging arms l0 and 13,- this spring preferably beingcoiled around the hub M, Fig. 2, and one end being anchored to the pin26, while the other end is located in one of aseries. of notches 21,Fig. 1; formed in the edge of a flange or fin integral .with the parts[3 and M. At'the rearward end of this series. of notches a lug 28, Fig.1, is provided where it can engage the lower end of a stop screw 33which is threaded through a hole in the web 3! which connects theopposite side pieces of the arm l0. This stop arrangement is useful. inadjusting the initial position of the cutter relatively to thecommutator, and the a to the commutator is clamped in the base, asillustrated in Fig. 1. At the beginning of the cutting operation on anyseparator, the part H3 is swung backwardly to the left, as shown indotted lines in Fig. 1, so that the cutter t8 canstart its operation atthe outer end of the commutator; By turning the screw 30 up or down, thecutter can be moved into the correct relationship to the commutator forthe start of the cutting operation; When this adjustment has once beenmade it is not disturbed until the work on that particular commutatorhas been completed. From the initial position shown in dotted lines insaid figure, the arm is moved toward the right, while revolving thecutter It. It cuts away the exposed surface of the separator rapidly,and its point of operation is transferred along the separator simply bymoving the arm l0 forward. When the undercutting operation on oneseparator has been completed, the Workman moves the arm Ill and thecutter l8 backwardly until the cutter clears the commutator. He thenturns the armature in the clamp 4-45 far enough to bring the nextadjacent separator into line with the cutter. The undercutting operationabove described is then repeated, and these operations are continueduntil all of the separators have been undercut to the desired degree.The entire operation may be performed rapidly with relatively littlee-ifort and with a high degree of accuracy because the depth of cut isdefinitely predetermined by the relationship between the diameter of thecutter and that of the gaging roll or collar 24.

If the nature of the equipment with which the commutator is turned downis such that the pulley and the bearing at the opposite end of the motorfrom the commutator need not be removed, then such removal is notrequired by the apparatus provided by this invention. At the conclusionof the operation the screw 5 is backed up sufficiently to release theshaft 1, after which the entire device is pulled off the shaft.

The labor involved in using this device can be further reduced bymounting a small electric motor on the bracket IE to drive the shaft l1.Such a construction is shown in Fig. 4 in which the motor is illustratedat 32. Or, provision may be made for driving the cutter shaft from someconvenient source of power through a flexible shaft, or in any otherconvenient manner. In some cases, also, it may be found desirable toclamp the apparatus directly to the core of the armature 8. This resultalso may be accomplished in the manner illustrated in Fig. 4. There thebase 2' on which the arm Ill is pivoted has two flexible elements 33-33secured rigidly to it at their upper ends and these parts are providedat their lower ends with blocks 34-34 through which a clamping bolt 35extends. By properly adjusting the parts on the motor and tightening upthe bolt 35, the undercutting apparatus may be mounted on the core sothat the cutter l8 can be operated in essentially the same manner abovedescribed in connection with Figs. 1, 2 and 3. In this arrangement thearmature presumably would be clamped in a vise and the bolt 35 would notbe tightened sufficiently to prevent the relative movement of thearmature and the undercutting apparatus necessary to shift the point ofoperation of the cutter from one separator to another. In addition toactually cutting away the edges of the separators, this apparatus alsois useful in cleaning oiit the grooves between the commutator segments,even when no substantial cutting away of the mica separators thus isrequired.

While I have herein shown and described a preferred embodiment of myinvention, it will be evident that the invention is susceptible ofembodiment in other forms without departing from the spirit or scopethereof. Also, since it is immaterial whether the commutator operatedupon is that of a motor of a generator, both will be hereinafterincluded generically in the term motori Having thus described myinvention, what I desire to claim as new is:

1. In an apparatus for operating on motor commutators, the combinationof a base, means for releasably securing a motor armature. to said base,a rotary cutter for operating on the mica separators between thesegments of the commutator, an arm pivoted on said base, and a secondarm pivoted on the first arm to swing in the same plane with it, saidsecond arm supporting said cutter.

2. An apparatus according to preceding claim 1, in combination with aspring connecting said arms and tending to swing one arm relatively tothe other to press said cutter against the commutator, and a stop screwcarried by one arm and against which said spring tends to hold the otherarm, said screw being adjustable to change the angular relationship ofsaid arms.

3. An apparatus according to preceding claim 1, in which said second armsupports a rotary shaft on which said cutter is mounted, and a rollloosely mounted on said shaft beside said cutter is arranged to run onthe surface of the commutator and is slightly smaller in diameter thanthe cutter, whereby it serves as a gage to limit the depth of operationof the cutter.

4. An apparatus according to preceding claim 1, in which said second armcarries a shaft on which said cutter is mounted, and a small motor ismounted onsaid arm to drive said shaft.

5. In an apparatus for operating on motor commutators, the combinationof a base, means for releasably securing a motor armature to said base,an arm pivoted on said base, a second arm pivoted to the first arm toswing in the same plane with it, a cutter mounted on said second arm. inposition to operate on the upper edges of the mica separators betweenthe segments of the commutator, and a spring associated with said secondarm and serving to press said cutter against the edges of saidseparators.

6. In an apparatus for operating on motor commutators, the combinationof a base, means for releasably securing a motor armature to said base,an arm pivoted on said base, a second arm pivoted to the first arm toswing in the same plane with it, a cutter mounted on the free end ofsaid second arm whereby it is supported in position to operatelengthwise on the upper edges of the separators between the segments ofthe commutator, a spring connecting said arms and serving to press saidcutter against the mica separators during such operation, and a stopscrew carried by one arm and adapted to engage the other to adjust theangular relationship between said arms.

CHARLES A. PAYNE.

